Green circle on the sun

[Chipper]

I shot thru a heavy fog directly into the rising sun. EOS 5D with no filter.
Image looks great on LCD monitor and on my computer at home.

When I printed it out, a green circle appears around the inside perimeter of the sun.

I could clone it out but it doesn't appear on my monitor.

I haven't edited the image from the camera other than cropping.

 Is there a color adjustment I should try? Color temp? Hue? Saturation?

Thanks,
 Chip[attachment=2488:attachment]

[bjanes]

I shot thru a heavy fog directly into the rising sun. EOS 5D with no filter.
Image looks great on LCD monitor and on my computer at home.

When I printed it out, a green circle appears around the inside perimeter of the sun.

I could clone it out but it doesn't appear on my monitor.

I haven't edited the image from the camera other than cropping.

 Is there a color adjustment I should try? Color temp? Hue? Saturation?

Thanks,

[a href=\"index.php?act=findpost&pid=117245\"][{POST_SNAPBACK}][/a]

Chip,

I think that the green circle that appears only in the print could be due to gamut limitations in the response of the printer. The central portion of the disc of the sun appears completely blown out in all channels and the appearance should be, and is, clipped to pure white. Luminance is decreasing at the edge of the disc and some channels are still clipped, while others are coming into gamut and can be displayed or printed while others can not, leading to color shifts, depending on the gamut of each device.

I would try to use soft proofing and the dodge tool (if you have Photoshop or something similar).

Bill

[Ray]

When I printed it out, a green circle appears around the inside perimeter of the sun.
[a href=\"index.php?act=findpost&pid=117245\"][{POST_SNAPBACK}][/a]

This is probably due to a combination of overexposure and lack of printer gamut, as Bill mentioned.

The color yellow is mainly a combination of red and green. With DSLRs the red channel tends to blow out before the green channel, so in an overexposed situation those lovely saturated yellows will experience a shift towards green as the red channel blows out. That shift might not be particularly noticeable on the monitor. There might still be enough red for the monitor to display a convincing yellow.

However, a lack of sufficient gamut of your printer, particularly with respect to yellow, can shift that balance even further towards green so that it becomes noticeable.

For scenes like this I'd recommend shooting RAW and converting the image into the ProPhoto RGB color space. (I get the impression the above image was a jpeg shot.)

Prophoto RGB has a wider color gamut than sRGB and Adobe RGB. It's particularly good with yellows.

[Christopher]

Bad printer profile.

[rdonson]

You've received some good responses on the cause.  I'm curious what the rendering intent was when you printed this and the printer/paper combination.

[Jonathan Wienke]

It could be a bad printer profile, or more likely, simply oversaturated color outside of the printer gamut. Try backing off the saturation of the sun where the green circle appears and see if that helps. If so, it's a simple gamut issue. If not, something else is going on and you may need to get a custom printer profile made. Contrary to Ray's advice, a wider-gamut working space will not solve the problem. The one you're currently using is probably larger than your printer gamut. There are many other good reasons to use a wide-gamut editing space, but the greatest is that you get to decide how to handle out-of-gamut colors, not the computer. But changing to a larger-gamut space by itself solves nothing.

[bjanes]

It could be a bad printer profile, or more likely, simply oversaturated color outside of the printer gamut. Try backing off the saturation of the sun where the green circle appears and see if that helps. If so, it's a simple gamut issue. If not, something else is going on and you may need to get a custom printer profile made.
[a href=\"index.php?act=findpost&pid=117535\"][{POST_SNAPBACK}][/a]

It could be a bad profile, but clipping occurs with good relative colorimetric profiles, while a perceptual rendering might have avoided it. The OP should tell us what printer he used, what profile, and what rendering intent. If he would post the original image and profile, then we could use gamut mapping software such as GamutVision to analyze the problem. Custom profiles are always a good idea, but many canned profiles from Epson and other vendors are often good enough for most of us, and a bit of manual tweaking of the image might solve the problem.

Contrary to Ray's advice, a wider-gamut working space will not solve the problem. The one you're currently using is probably larger than your printer gamut. There are many other good reasons to use a wide-gamut editing space, but the greatest is that you get to decide how to handle out-of-gamut colors, not the computer. But changing to a larger-gamut space by itself solves nothing.
[a href=\"index.php?act=findpost&pid=117535\"][{POST_SNAPBACK}][/a]

I agree that a wider working space would not likely resolve the problem, since the clipping did not occur during the raw conversion and encoding into the selected color space as evidenced by the absence of the artifact on screen. The OP did not say what printer or working space he was using, but current photo inkjet printers certainly exceed sRGB and aRGB gamut in the yellows and greens at L* of around 50 as shown in this interactive gamut plot from DryCreek.com. However, at luminances approaching 100, the monitor gamut is larger. Shape of the gamuts is often important.

[attachment=2493:attachment]

A wider working space should be used if clipping is evident during the raw conversion, as evidenced by color spikes at the end of the histogram in Adobe Camera Raw.

[Ray]

Contrary to Ray's advice, a wider-gamut working space will not solve the problem.
[a href=\"index.php?act=findpost&pid=117535\"][{POST_SNAPBACK}][/a]

Maybe not. However, I have noticed with ultrachrome inks on my Epson 7600 a slight shift in saturated yellows towards green within the Adobe RGB color space, which isn't apparent in ProPhoto RGB.

Of course, there could have been some other unidentified cause, but having seen it once I've become a ProPhoto convert.

[bjanes]

Maybe not. However, I have noticed with ultrachrome inks on my Epson 7600 a slight shift in saturated yellows towards green within the Adobe RGB color space, which isn't apparent in ProPhoto RGB.

Of course, there could have been some other unidentified cause, but having seen it once I've become a ProPhoto convert.
[a href=\"index.php?act=findpost&pid=117644\"][{POST_SNAPBACK}][/a]

Ray,

Since you are using a printer with a fairly wide gamut, it is wise to use ProPhotoRGB since it can contain the entire gamut of the printer, whereas Adobe RGB does not. However, if the gamut of your image fits into sRGB (as shown by the lack of clipping in Adobe Camera Raw), there is no advantage of the wider working space. In fact, there is a disadvantage with the wider space in that ProPhotoRGB really requires 16 bits, whereas you can get away with 8 bits in the narrower spaces mentioned.

Since most of us do not examine each image individually for gamut, it makes sense to use ProPhotoRGB when you are processing a group of images.

Bill

[Ray]

Since most of us do not examine each image individually for gamut, it makes sense to use ProPhotoRGB when you are processing a group of images.
[a href=\"index.php?act=findpost&pid=117650\"][{POST_SNAPBACK}][/a]

Exactly! I shoot RAW. I convert into ProPhot RGB and 16 bit whether the image needs it or not. My monitor is calibrated and I expect to see on the print what I see on my monitor with proof colors ticked under 'view' in PS.